Imaging lens and electronic apparatus having the same

ABSTRACT

An optical imaging lens includes first, second, third, fourth and fifth lens elements arranged sequentially from an object side to an image side along an optical axis. The image-side surface of the first lens element comprises a concave portion in a vicinity of the optical axis. The object-side surface of the fourth lens element comprises a concave portion in a vicinity of the optical axis. The optical imaging lens as a whole has only the five lens elements having refractive power.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/642,064, filed on Jul. 5, 2017, which is a continuation of U.S.patent application Ser. No. 14/685,408, filed on Apr. 13, 2015, now U.S.Pat. No. 9,739,979, which is a continuation of U.S. patent applicationSer. No. 14/540,885, filed on Nov. 13, 2014, now U.S. Pat. No.9,052,493, which is a continuation of U.S. patent application Ser. No.13/617,632, filed on Sep. 14, 2012, now U.S. Pat. No. 8,953,255, whichclaims priority of Taiwan Patent Application No. 101111479, filed onMar. 30, 2012, the contents of which are hereby incorporated byreference in their entirety for all purposes.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to an imaging lens and an electronicapparatus, more particularly to an imaging lens having five lenselements and an electronic apparatus having the same.

2. Description of the Related Art

In recent years, as portable electronic devices (e.g., mobile phones anddigital cameras) have become ubiquitous, considerable effort has beenput into reducing the dimensions of portable electronic devices. As thedimensions of charged coupled device (CCD) and complementary metal-oxidesemiconductor (CMOS) based optical sensors are reduced, the dimensionsof imaging lens for use with the optical sensors must be accordinglyreduced without significantly compromising optical performance.

In view of the above: U.S. Pat. No. 7,480,105 discloses a conventionalimaging lens with five lens elements, of which the first, second, andthird lens elements have negative, positive, and negative refractivepowers, respectively. U.S. Pat. No. 7,639,432 discloses a conventionalimaging lens with five lens elements, of which the first, second, andthird lens elements have negative, positive, and positive refractivepowers, respectively; and each of U.S. Pat. Nos. 7,486,449 and 7,684,127discloses a conventional imaging lens with five lens elements, of whichthe first, second, and third lens elements have negative, negative, andpositive refractive powers, respectively. However, the aboveconventional imaging lenses have system lengths ranging from 10 mm to 18mm, which may be too long for use in certain miniaturized electronicapparatuses.

Moreover, each of U.S. Patent Application Publication Nos. 2011/0013069and 2011/0249346 and U.S. Pat. No. 8,000,030 discloses a conventionalimaging lens with a system length of approximately 6 mm, and having fivelens elements, of which the first, second, and third lens elements havepositive, negative, and negative refractive powers, respectively.However, due to surface configurations of the third, fourth and fifthlens elements of each of the conventional imaging lenses, a satisfactorytradeoff between system length and aberration of the conventionalimaging lens may be difficult to achieve. In other words, withoutsignificantly compromising the imaging quality, the system lengths ofthe conventional imaging lenses may not be effectively reduced.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an imaging lens havinga shorter overall length while maintaining good optical performance.

An optical imaging lens includes, sequentially from an object side to animage side, first, second, third, fourth and fifth lens elements. Eachof the first, second, third, fourth and fifth lens elements has anobject-side surface facing toward the object side and an image-sidesurface facing toward the image side. The object-side surface of thefirst lens element comprises a convex portion in a vicinity of anoptical axis. The image-side surface of the second lens elementcomprises a concave portion in a vicinity of its periphery. Theobject-side surface of the third lens element comprises a concaveportion in a vicinity of its periphery. The fourth lens element haspositive refractive power. The image-side surface of the fifth lenselement comprises a convex portion in a vicinity of its periphery. Theoptical imaging lens as a whole has only the five lens elements havingrefractive power.

The imaging lens does not include any lens element with refractive powerother than the first, second, third, fourth and fifth lens elements. Inan embodiment, a sum of thicknesses of all five lens elements along theoptical axis is ALT, a central thickness of the fourth lens elementalong the optical axis is T4, an air gap between the fourth lens elementand fifth lens element along the optical axis is G45, and ALT, T4 andG45 satisfy the equation:

2.2≤ALT/(T4+G45)≤3.12.

In one embodiment, a sum of all four air gaps from the first lenselement to the fifth lens element along the optical axis is G_(all-air),an air gap between the first lens element and the second lens elementalong the optical axis is G12, an air gap between the third lens elementand the fourth lens element along the optical axis is G34, andG_(all-air), G12 and G34 satisfy the equation:2.1≤G_(all-air)/(G12+G34)≤4.5.

In one embodiment, an effective system focal length is EFL, a centralthickness of the first lens element along the optical axis is T1, acentral thickness of the second lens element along the optical axis isT2, a central thickness of the third lens element along the optical axisis T3, and EFL, T1, T2 and T3 satisfy the equation:2.9≤EFL/(T1+T2+T3)≤3.47.

In one embodiment, a distance between the object-side of said first lenselement and an image plane along the optical axis is TTL, and TTL, T1and T2 satisfy the equation:

5.0≤TTL/(T1+T2)≤5.6.

Another object of the present invention is to provide an electronicapparatus having an imaging lens with five lens elements.

An electronic apparatus of the present invention includes a housing andan imaging module. The imaging module is disposed in the housing andincludes the imaging lens of the present invention, a barrel whereat theimaging lens is disposed, a holder unit on which the barrel is disposed,a substrate on which the holder unit is disposed, and an image sensordisposed on the substrate and at the image side and operativelyassociated with the imaging lens for capturing images.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the present invention will becomeapparent in the following detailed description of the preferredembodiments with reference to the accompanying drawings, of which:

FIG. 1 is a schematic diagram that illustrates the first preferredembodiment of an imaging lens according to the present invention;

FIG. 2 shows values of some optical parameters corresponding to theimaging lens of the first preferred embodiment;

FIG. 3 shows values of some parameters of an optical equationcorresponding to the imaging lens of the first preferred embodiment;

FIGS. 4(a) to 4(d) show different optical characteristics of the imaginglens of the first preferred embodiment;

FIG. 5 is a schematic diagram that illustrates the second preferredembodiment of an imaging lens according to the present invention;

FIG. 6 shows values of some optical parameters corresponding to theimaging lens of the second preferred embodiment;

FIG. 7 shows values of some parameters of the optical equationcorresponding to the imaging lens of the second preferred embodiment;

FIGS. 8(a) to 8(d) show different optical characteristics of the imaginglens of the second preferred embodiment;

FIG. 9 is a schematic diagram that illustrates the third preferredembodiment of an imaging lens according to the present invention;

FIG. 10 shows values of some optical parameters corresponding to theimaging lens of the third preferred embodiment;

FIG. 11 shows values of some parameters of the optical equationcorresponding to the imaging lens of the third preferred embodiment;

FIGS. 12(a) to 12(d) show different optical characteristics of theimaging lens of the third preferred embodiment;

FIG. 13 is a schematic diagram that illustrates the fourth preferredembodiment of an imaging lens according to the present invention;

FIG. 14 shows values of some optical parameters corresponding to theimaging lens of the fourth preferred embodiment;

FIG. 15 shows values of some parameters of the optical equationcorresponding to the imaging lens of the fourth preferred embodiment;

FIGS. 16(a) to 16(d) show different optical characteristics of theimaging lens of the fourth preferred embodiment;

FIG. 17 is a table that shows values of parameters of other opticalrelationships corresponding to the imaging lenses of the first, second,third, and fourth preferred embodiments;

FIG. 18 is a schematic partly sectional view to illustrate a firstexemplary application of the imaging lens of the present invention;

FIG. 19 is a schematic partly sectional view to illustrate a secondexemplary application of the imaging lens of the present invention; and

FIG. 20 is a perspective cutaway view to illustrate an extending portionof a first lens element of the imaging lens of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Before the present invention is described in greater detail, it shouldbe noted that like elements are denoted by the same reference numeralsthroughout the disclosure.

Referring to FIG. 1, the first preferred embodiment of an imaging lens 2of the present invention includes an aperture stop 8, first, second,third, fourth, and fifth lens elements 3-7, and an optical filter 9arranged in the given order along an optical axis (I) from an objectside to an image side. The optical filter 9 is an infrared cut filterfor reducing the transmission of infrared light to thereby reduce coloraberration of images formed at an image plane 10.

Each of the first, second, third, fourth, and fifth lens elements 3-7and the optical filter 9 has an object-side surface 31, 41, 51, 61, 71,91 facing toward the object side, and an image-side surface 32, 42, 52,62, 72, 92 facing toward the image side. Light entering the imaging lens2 travels through the aperture stop 8, the object-side and image-sidesurfaces 31, 32 of the first lens element 3, the object-side andimage-side surfaces 41, 42 of the second lens element 4, the object-sideand image-side surfaces 51, 52 of the third lens element 5, theobject-side and image-side surfaces 61, 62 of the fourth lens element 6,the object-side and image-side surfaces 71, 72 of the fifth lens element7, and the object-side and image-side surfaces 91, 92 of the opticalfilter 9, in the given order, to form an image on the image plane 10.

The first lens element 3 has a positive refractive power, theobject-side surface 31 thereof is a convex surface, and the image-sidesurface 32 thereof has a concave portion 321 that is in a vicinity ofthe optical axis (I) and a convex portion 322 that is in a vicinity of aperiphery of the first lens element 3.

The second lens element 4 has a negative refractive power, theobject-side surface 41 thereof is a convex surface having a convexportion 411 in a vicinity of a periphery of the second lens element 4,and the image-side surface 42 thereof is a concave surface.

The third lens element 5 has a negative refractive power, theobject-side surface 51 thereof has a convex portion 511 in a vicinity ofthe optical axis (I) and a concave portion 512 in a vicinity of aperiphery of the third lens element 5, and the image-side surface 52thereof has a concave portion 521 in a vicinity of the optical axis (I)and a convex portion 522 in a vicinity of the periphery of the thirdlens element 5.

The fourth lens element 6 has a positive refractive power, theobject-side surface 61 thereof is a concave surface, and the image-sidesurface 62 thereof is a convex surface.

The fifth lens element 7 has a negative refractive power. Theobject-side surface 71 of the fifth lens element 5 has a first convexportion 711 in a vicinity of the optical axis (I) and a second convexportion 712 in a vicinity of a periphery of the fifth lens element 7.The image-side surface 72 of the fifth lens element 5 has a concaveportion 721 in a vicinity of the optical axis (I) and a convex portion722 in a vicinity of the periphery of the fifth lens element 7.

The imaging lens 2 of the present invention does not include any lenselement with refractive power other than the abovementioned first,second, third, fourth and fifth lens elements 3-7, which are made ofplastic material in this embodiment. The object-side surfaces 31-71 andthe image-side surfaces 32-72 of the lens elements 3-7 are aspherical inthis embodiment. However, configurations of the object-side andimage-side surfaces 31-71, 32-72 are not limited to such.

Relationships among some optical parameters corresponding to the firstpreferred embodiment are as follows:

T₂/G_(all-air)=0.30

T₃/G_(all-air)=0.32

|υ₂−υ₃1=6.02035

f₄/G_(all-air)=6.11363

where:

“T₂” represents a distance between the object-side and image-sidesurfaces 41, 42 of the second lens element 4 at the optical axis (I);

“T₃” represents a distance between the object-side and image-sidesurfaces 51, 52 of the third lens element 5 at the optical axis (I)

“υ₂” represents a dispersion coefficient of the second lens element 4;

“υ₃” represents a dispersion coefficient of the third lens element 5;

“G_(all-air)” represents a sum of widths of a clearance between theimage-side and object-side surfaces 32, 41 at the optical axis (I), aclearance between the image-side and object-side surfaces 42, 51 at theoptical axis (I), a clearance between the image-side and object-sidesurfaces 52, 61 at the optical axis (I), and a clearance between theimage-side and object-side surfaces 62, 71 at the optical axis (I)(i.e., “G_(all-air)” represents a sum of widths of clearances among theimaging lenses 3-7); and

“f₄” represents a focal length of the fourth lens elements 6.

The imaging lens 2 of the first preferred embodiment has an overallsystem focal length of 3.27004 mm and a half field-of-view (HFOV) of35.12°. Shown in FIG. 2 is a table that shows values of some opticalparameters corresponding to the surfaces 31-71, 32-72 of the firstpreferred embodiment.

Each of the object-side surfaces 31-71 and the image-side surfaces 32-72satisfies the optical equation of

${X(Y)} = {{\frac{Y^{2}}{R}/( {1 + \sqrt{1 - {( {1 + K} )\frac{Y^{2}}{R^{2}}}}} )} + {\sum\limits_{i = 1}{a_{21} \times Y^{2\; i}}}}$

where:

“X” represents a distance from a tangential plane, which is tangent to apoint of the surface intersecting with the optical axis (I), to anarbitrary point of the surface;

“Y” represents a distance between the arbitrary point of the surface andthe optical axis (I);

“R” represents a radius of curvature of the surface;

“K” represents a conic constant of the surface; and

“a_(2i)” represents a 2i^(th)-order coefficient of the surface.

Shown in FIG. 3 is a table that shows values of some optical parametersof the above optical equation corresponding to the first preferredembodiment.

FIGS. 4(a) to 4(d) show simulation results corresponding to longitudinalspherical aberration, sagittal astigmatism aberration, tangentialastigmatism aberration, and distortion aberration of the first preferredembodiment, respectively. In each of the simulation results, curvescorresponding respectively to wavelengths of 470 nm, 555 nm, and 650 nmare shown.

It can be understood from FIG. 4(a) that, since each of the curvescorresponding to longitudinal spherical aberration has a focal length ateach field of view (indicated by the vertical axis) that falls withinthe range of ±0.01 mm, the first preferred embodiment is able to achievea relatively low spherical aberration at each of the wavelengths.Furthermore, since a deviation in focal length among the curves at eachfield of view does not exceed the range of ±0.02 mm, the first preferredembodiment has a relatively low chromatic aberration.

It can be understood from FIGS. 4(b) and 4(c) that, since each of thecurves corresponding to sagittal astigmatism aberration falls within therange of ±0.06 mm of focal length, and each of the curves correspondingto tangential astigmatism aberration falls within the range of ±0.025 mmof focal length, the first preferred embodiment has a relatively lowoptical aberration. Further, since a difference among the curves in FIG.4(b) and a difference among the curves in FIG. 4(c) are relativelysmall, the first preferred embodiment has a relatively reduceddistortion.

Moreover, as shown in FIG. 4(d), since each of the curves correspondingto distortion aberration falls within the range of ±2.5%, the firstpreferred embodiment is able to meet requirements in imaging quality ofmost optical systems.

In view of the above, with the system length reduced down to below 4 mm,the imaging lens 2 of the first preferred embodiment is still able toachieve a relatively good optical performance.

Referring to FIG. 5, the difference between the first and secondpreferred embodiments resides in that, in the second preferredembodiment, the image-side surface 32 of the first lens element 31 is aconvex surface, and the imaging lens 2 has an overall system focallength of 3.25285 mm and an HFOV of 35.18°.

Relationships among some optical parameters corresponding to the secondpreferred embodiment are as follows:

T₂/G_(all-air)=0.33

T₃/G_(all-air)=0.40

|v₂−v₃1=2.76061

f₄/G_(all-air)=5.59827

Shown in FIG. 6 is a table that shows values of some optical parameterscorresponding to the surfaces 31-71, 32-72 of the second preferredembodiment.

Shown in FIG. 7 is a table that shows values of some optical parametersof the optical equation mentioned hereinabove corresponding to thesecond preferred embodiment.

FIGS. 8(a) to 8(d) show simulation results corresponding to longitudinalspherical aberration, sagittal astigmatism aberration, tangentialastigmatism aberration, and distortion aberration of the secondpreferred embodiment, respectively. It is apparent that the secondpreferred embodiment is able to achieve low spherical, chromaticaberrations and distortion even when the system length is reduced downto 4 mm.

Shown in FIG. 9 is the third preferred embodiment, which, in comparisonwith the first preferred embodiment, has an overall system focal lengthof 3.25954 mm and an HFOV of 35.12°.

Relationships among some optical parameters corresponding to the thirdpreferred embodiment are as follows:

T₂/G_(all-air)=0.40

T₃/G_(all-air)=0.49

|v₂−v₃1=0.00

f₄/G_(all-air)=6.76944

Shown in FIG. 10 is a table that shows values of some optical parameterscorresponding to the surfaces 31-71, 32-72 of the third preferredembodiment.

Shown in FIG. 11 is a table that shows values of some optical parametersof the abovementioned optical equation corresponding to the thirdpreferred embodiment.

Referring to 12(a) to 12(d), the third preferred embodiment is also ableto achieve relatively good optical performance while reducing the systemlength down to 4 mm.

Referring to FIG. 13, the difference between the first and fourthpreferred embodiments of this invention resides in that, in the fourthpreferred embodiment, the object-side surface 51 of the third lenselement 5 is a concave surface, and the image-side surface 52 of thesame is formed with a convex portion 521′, instead of the concaveportion 521, in the vicinity of the optical axis (I). In comparison withthe first preferred embodiment, the imaging lens 2 of this embodimenthas an overall system focal length of 3.36 mm and an HFOV of 34.64°.

Relationships among some optical parameters corresponding to the fourthpreferred embodiment are as follows:

T₂/G_(all-air)=0.28975

T₃/G_(all-air)=0.35319

|v₂−v₃1=0.00

f₄/G_(all-air)=5.44178

Shown in FIG. 14 is a table that shows values of some optical parameterscorresponding to the surfaces 31-71, 32-72 of the fourth preferredembodiment.

Shown in FIG. 15 is a table that shows values of some optical parametersof the abovementioned optical equation corresponding to the fourthpreferred embodiment.

Referring to 16(a) to 16(d), it is apparent that the fourth preferredembodiment is able to achieve low spherical, chromatic aberrations anddistortion even when the system length is reduced down to 4 mm.

Shown in FIG. 17 is a table that shows some of the aforesaidrelationships corresponding to each of the preferred embodiments forcomparison.

Effects of the various optical parameters on the imaging quality aredescribed hereinafter.

When the imaging lens 2 satisfies the relationships of0.28<T₂/G_(all-air)<0.48, 0.30<T₃/G_(all-air)<0.50 and5.0<f₄/G_(all-air)<7.0, the system length may be effectively reducedwithout significantly compromising the optical performance. When theimaging lens 2 fails to satisfy these relationships, a thickness of oneof the second lens element 4 and the third lens element 5 may be toosmall and/or the sum of the widths of the clearances among the lenselements 3-7 may be too large (T₂/G_(all-air)<0.28, T₃/G_(all-air)<0.3,and f₄/G_(all-air)<5), the former of which may increase difficulty ofmanufacturing, and the latter of which may increase difficulty ofreducing the system length. Alternatively, the thickness of one of thesecond lens element 4 and the third lens element 5 may be too largeand/or the sum of the widths of the clearances among the lens elements3-7 may be too small (T₂/G_(all-air)>0.48, T₃/G_(all-air)>0.5, andF₄/G_(all-air)>7), which may significantly compromise the opticalperformance of the imaging lens 2.

Preferably, the imaging lens 2 satisfies 0.28<T₂/G_(all-air)<0.42.

When the imaging lens 2 satisfies |v₂−v₃|<10, a difference between Abbenumbers of the second and third lens elements 4, 5 is sufficiently smallsuch that the second and third lens elements 4, 5 may cooperate toprovide a negative refractive power for matching the refractive powersof the remaining lens elements 3, 6, 7.

By virtue of the positive refractive power of the first lens element 3,the negative refractive power of the second lens element 4, and the Abbenumbers of the second and third lens elements 4, 5, aberrationsattributed to the first lens element 3 are relative reduced. Moreover,by virtue of the negative refractive power of the third lens element 5,the imaging lens 2 is able to achieve the effect of field curvaturecorrection. Furthermore, the convex portion 522 of the image-sidesurface 52 of the third lens element 5, the concave object-side surface61 of the fourth lens element 6, and the convex portion 711 of theobject-side surface 71 of the fifth lens element 7 may be matched indesign to cooperatively reduce aberration and to achieve a betterimaging quality.

Through disposing the aperture stop 8 at the object-side surface 31 ofthe first lens element 3, off-axis light may enter the image plane 10 ina quite horizontal direction, thereby facilitating length reduction ofimaging lens 2.

Since the imaging lens 2 of the present invention satisfies theaforementioned relationships among the optical parameters “T₂”, “T₃”,“G_(all-air)”, and “f₄”, the imaging lens 2 is able to achieve reducedspherical aberration, which, together with the surface configurations ofthe lens elements 3-7, enables the imaging lens 2 to achieve reducedspherical and chromatic aberrations even when the overall system lengthis reduced to 4 mm.

Shown in FIG. 18 is a first exemplary application of the imaging lens 2,in which the imaging lens 2 is disposed in a housing 11 of an electronicapparatus 1 (such as a mobile phone), and forms a part of an imagingmodule 12 of the electronic apparatus 1. The imaging module 12 includesa barrel 121 whereat the imaging lens 2 is disposed, a holder unit 122on which the barrel 121 is disposed, a substrate 123 on which the holderunit 122 is disposed, and an image sensor 124 disposed on the substrate123 and at the image plane 10 of the imaging lens 2, and operativelyassociated with the imaging lens 2 for capturing images.

Shown in FIG. 19 is a second exemplary application, which differs fromthe first exemplary application in that the holder unit 122 includes avoice-coil motor (VCM) 125 on which the barrel 121 is disposed, and asensor seat 126. The VCM 125 includes a first portion 127 sleeved ontothe barrel 121 and movable along the optical axis (I), a second portion128 disposed on the sensor seat 126 and disposed at an outer side of thefirst portion 127, a magnet 129 disposed on the second portion 128 andinterposed between the first and second portions 127, 128, and a coil130 wound on the first portion 127.

The first portion 127 is movable, together with the imaging lens 2 inthe barrel 121, along the optical axis (I) for focusing of the imaginglens 2. The optical filter 9, on the other hand, is disposed on thesensor seat 126. Other components of the electronic apparatus 1 of thesecond exemplary application are identical in configuration andstructure to those of the first exemplary application, and will not bedescribed hereinafter for the sake of brevity.

Referring to FIG. 20, during manufacture, the first lens element 3 maybe formed with an extending portion 33, which may be flat or stepped inshape. In terms of function, while the object-side and image-sidesurfaces 31, 32 are configured to enable passage of light through thefirst lens element 3, the extending portion 33 merely serves to providethe function of installation and does not contribute toward passage oflight through the first lens element 3. The other lens elements 4-7 mayalso be formed with extending portions similar to that of the first lenselement 3.

In summary, with the system length of the imaging lens 2 reduced tobelow 4 mm without compromising optical performance, the imaging lens 2of the present invention is suitable for use in various electronicapparatuses with relatively small dimensions, such as those exemplifiedin the above exemplary applications. Since dimensions of the electronicapparatuses are reduced, the amount of material and hence cost requiredfor manufacturing the electronic apparatuses are also reduced.

While the present invention has been described in connection with whatare considered the most practical and preferred embodiments, it isunderstood that this invention is not limited to the disclosedembodiments but is intended to cover various arrangements includedwithin the spirit and scope of the broadest interpretation so as toencompass all such modifications and equivalent arrangements.

What is claimed is:
 1. An optical imaging lens comprising first, second,third, fourth, and fifth lens elements arranged from an object side toan image side in a given order along an optical axis of the opticalimaging lens, each of the first, second, third, fourth and fifth lenselements having an object-side surface facing toward the object side toallow imaging rays to pass therethrough and an image-side surface facingtoward the image side to allow the imaging rays to pass therethrough,wherein: the image-side surface of the first lens element has a concaveportion in a vicinity of the optical axis; the object-side surface ofthe fourth lens element has a concave portion in a vicinity of theoptical axis; the optical imaging lens as a whole has only the five lenselements having refractive power; and an effective system focal lengthis EFL, a central thickness of the first lens element along the opticalaxis is T1, an air gap between the first lens element and second lenselement along the optical axis is G12, and EFL, T1 and G12 satisfy theequation:5.7≤EFL/(T1+G12)≤6.3.
 2. The optical imaging lens as claimed in claim 1,wherein an air gap between the second lens element and the third lenselement along the optical axis is G23, a central thickness of the thirdlens element along the optical axis is T3, and EFL, G23 and T3 satisfythe equation:4.89≤EFL/(G23+T3)≤5.88.
 3. The optical imaging lens as claimed in claim1, wherein an air gap between the fourth lens element and the fifth lenselement along the optical axis is G45, a central thickness of the fifthlens element along the optical axis is T5, and EFL, G45 and T5 satisfythe equation:4.7≤EFL/(G45+T5)≤6.3.
 4. The optical imaging lens as claimed in claim 1,wherein a sum of thicknesses of all five lens elements along the opticalaxis is ALT, an air gap between the fourth lens element and the fifthlens element along the optical axis is G45, and ALT and G45 satisfy theequation:5.88≤ALT/G45≤19.21.
 5. The optical imaging lens as claimed in claim 1,wherein a distance between the object-side surface of the first lenselement and an image plane along the optical axis is TTL, an air gapbetween the second lens element and the third lens element along theoptical axis is G23, an air gap between the third lens element and thefourth lens element along the optical axis is G34, and TTL, G23 and G34satisfy the equation:6.99≤TTL/(G23+G34)≤8.03.
 6. The optical imaging lens as claimed in claim1, wherein a distance between the image-side surface of the fifth lenselement and an image plane along the optical axis is BFL, an air gapbetween the fourth lens element and the fifth lens element along theoptical axis is G45, and BFL, G12 and G45 satisfy the equation:2.98≤BFL/(G12+G45)≤6.12.
 7. The optical imaging lens as claimed in claim1, wherein a sum of thicknesses of all five lens elements along theoptical axis is ALT, a central thickness of the third lens element alongthe optical axis is T3, an air gap between the third lens element andthe fourth lens element along the optical axis is G34, and ALT, T3 andG34 satisfy the equation:3.6≤ALT/(T3+G34)≤4.6.
 8. An optical imaging lens comprising first,second, third, fourth, and fifth lens elements arranged from an objectside to an image side in a given order along an optical axis of theoptical imaging lens, each of the first, second, third, fourth and fifthlens elements having an object-side surface facing toward the objectside to allow imaging rays to pass therethrough and an image-sidesurface facing toward the image side to allow the imaging rays to passtherethrough, wherein: the image-side surface of the first lens elementhas a concave portion in a vicinity of the optical axis; the image-sidesurface of the second lens element has a concave portion in a vicinityof the optical axis; the object-side surface of the fourth lens elementhas a concave portion in a vicinity of the optical axis; the opticalimaging lens as a whole has only the five lens elements havingrefractive power; and a sum of thicknesses of all five lens elementsalong the optical axis is ALT, an air gap between the second lenselement and the third lens element along the optical axis is G23, an airgap between the third lens element and the fourth lens element along theoptical axis is G34, and ALT, G23 and G34 satisfy the equation:3.4≤ALT/(G23+G34)≤4.2.
 9. The optical imaging lens as claimed in claim8, wherein a distance between the object-side surface of the first lenselement and the image-side surface of the fifth lens element along theoptical axis is TL and a central thickness of the third lens elementalong the optical axis is T3, and TL, G23 and T3 satisfy the equation:4.13≤TL/(G23+T3)≤4.69.
 10. The optical imaging lens as claimed in claim8, wherein an effective system focal length is EFL, a central thicknessof the second lens element along the optical axis is T2, a centralthickness of the third lens element along the optical axis is T3, andEFL, T2 and T3 satisfy the equation:5.10≤EFL/(T2+T3)≤6.88.
 11. The optical imaging lens as claimed in claim8, wherein a sum of thicknesses of all five lens elements along theoptical axis is ALT, an air gap between the first lens element and thesecond lens element along the optical axis is G12, and ALT, G12 and G23satisfy the equation:4.77≤ALT/(G12+G23)≤5.82.
 12. The optical imaging lens as claimed inclaim 8, wherein a distance between the object-side surface of the firstlens element and an image plane along the optical axis is TTL, a centralthickness of the first lens element along the optical axis is T1, acentral thickness of the second lens element along the optical axis isT2, and TTL, T1 and T2 satisfy the equation:5.0≤TTL/(T1+T2)≤5.6.
 13. The optical imaging lens as claimed in claim 8,wherein a central thickness of the third lens element along the opticalaxis is T3, a central thickness of the fourth lens element along theoptical axis is T4, a central thickness of the fifth lens element alongthe optical axis is T5, and T3, T4 and T5 satisfy the equation:1.7≤(T3/T4)+(T4/T5)≤2.3.
 14. The optical imaging lens as claimed inclaim 8, wherein a sum of all four air gaps from the first lens elementto the fifth lens element along the optical axis is G_(all-air), an airgap between the first lens element and the second lens element along theoptical axis is G12, and G_(all-air), G12 and G34 satisfy the equation:2.1≤G _(all-air)/(G12+G34)≤4.5.
 15. An optical imaging lens comprisingfirst, second, third, fourth, and fifth lens elements arranged from anobject side to an image side in a given order along an optical axis ofthe optical imaging lens, each of the first, second, third, fourth andfifth lens elements having an object-side surface facing toward theobject side to allow imaging rays to pass therethrough and an image-sidesurface facing toward the image side to allow the imaging rays to passtherethrough, wherein: the image-side surface of the first lens elementhas a concave portion in a vicinity of the optical axis; the object-sidesurface of the third lens element has a concave portion in a vicinity ofits periphery; the object-side surface of the fourth lens element has aconcave portion in a vicinity of the optical axis; the optical imaginglens as a whole has only the five lens elements having refractive power;and a sum of thicknesses of all five lens elements along the opticalaxis is ALT, an air gap between the second lens element and the thirdlens element along the optical axis is G23, an air gap between the thirdlens element and the fourth lens element along the optical axis is G34,and ALT, G23 and G34 satisfy the equation:3.4≤ALT/(G23+G34)≤4.2.
 16. The optical imaging lens as claimed in claim15, wherein a sum of all four air gaps from the first lens element tothe fifth lens element along the optical axis is G_(all-air), a centralthickness of the third lens element along the optical axis is T3, andG_(all-air), G23 and T3 satisfy the equation:1.08≤G _(all-air)/(G23+T3)≤1.4.
 17. The optical imaging lens as claimedin claim 15, wherein an effective system focal length is EFL, a centralthickness of the first lens element along the optical axis is T1, acentral thickness of the second lens element along the optical axis isT2, a central thickness of the third lens element along the optical axisis T3, and EFL, T1, T2 and T3 satisfy the equation:2.9≤EFL/(T1+T2+T3)≤3.47.
 18. The optical imaging lens as claimed inclaim 15, wherein a central thickness of the fourth lens element alongthe optical axis is T4, an air gap between the fourth lens element andfifth lens element along the optical axis is G45, and ALT, T4 and G45satisfy the equation:2.2≤ALT/(T4+G45)≤3.12.
 19. The optical imaging lens as claimed in claim15, wherein a central thickness of the second lens element along theoptical axis is T2, a central thickness of the third lens element alongthe optical axis is T3, and T2, G23 and T3 satisfy the equation:2.5≤(T2+G23+T3)/G23≤3.1.
 20. The optical imaging lens as claimed inclaim 15, wherein a central thickness of the third lens element alongthe optical axis is T3, a sum of all four air gaps from the first lenselement to the fifth lens element along the optical axis is G_(all-air),and T3 and G_(all-air) satisfy the equation:0.3≤T3/G _(all-air)≤0.5.